Files
linux/drivers/iommu/amd/Kconfig
Alejandro Jimenez 789a5913b2 iommu/amd: Use the generic iommu page table
Replace the io_pgtable versions with pt_iommu versions. The v2 page table
uses the x86 implementation that will be eventually shared with VT-d.

This supports the same special features as the original code:
 - increase_top for the v1 format to allow scaling from 3 to 6 levels
 - non-present flushing
 - Dirty tracking for v1 only
 - __sme_set() to adjust the PTEs for CC
 - Optimization for flushing with virtualization to minimize the range
 - amd_iommu_pgsize_bitmap override of the native page sizes
 - page tables allocate from the device's NUMA node

Rework the domain ops so that v1/v2 get their own ops. Make dedicated
allocation functions for v1 and v2. Hook up invalidation for a top change
to struct pt_iommu_flush_ops. Delete some of the iopgtable related code
that becomes unused in this patch. The next patch will delete the rest of
it.

This fixes a race bug in AMD's increase_address_space() implementation. It
stores the top level and top pointer in different memory, which prevents
other threads from reading a coherent version:

   increase_address_space()   alloc_pte()
                                level = pgtable->mode - 1;
	pgtable->root  = pte;
	pgtable->mode += 1;
                                pte = &pgtable->root[PM_LEVEL_INDEX(level, address)];

The iommupt version is careful to put mode and root under a single
READ_ONCE and then is careful to only READ_ONCE a single time per
walk.

Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Tested-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Tested-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
2025-11-05 09:08:56 +01:00

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# SPDX-License-Identifier: GPL-2.0-only
# AMD IOMMU support
config AMD_IOMMU
bool "AMD IOMMU support"
select SWIOTLB
select PCI_MSI
select PCI_ATS
select PCI_PRI
select PCI_PASID
select IRQ_MSI_LIB
select MMU_NOTIFIER
select IOMMU_API
select IOMMU_IOVA
select IOMMU_SVA
select IOMMU_IOPF
select IOMMUFD_DRIVER if IOMMUFD
select GENERIC_PT
select IOMMU_PT
select IOMMU_PT_AMDV1
select IOMMU_PT_X86_64
depends on X86_64 && PCI && ACPI && HAVE_CMPXCHG_DOUBLE
help
With this option you can enable support for AMD IOMMU hardware in
your system. An IOMMU is a hardware component which provides
remapping of DMA memory accesses from devices. With an AMD IOMMU you
can isolate the DMA memory of different devices and protect the
system from misbehaving device drivers or hardware.
You can find out if your system has an AMD IOMMU if you look into
your BIOS for an option to enable it or if you have an IVRS ACPI
table.
config AMD_IOMMU_DEBUGFS
bool "Enable AMD IOMMU internals in DebugFS"
depends on AMD_IOMMU && IOMMU_DEBUGFS
help
!!!WARNING!!! !!!WARNING!!! !!!WARNING!!! !!!WARNING!!!
DO NOT ENABLE THIS OPTION UNLESS YOU REALLY, -REALLY- KNOW WHAT YOU ARE DOING!!!
Exposes AMD IOMMU device internals in DebugFS.
This option is -NOT- intended for production environments, and should
not generally be enabled.